How long for not sitting after fat grafting to the hips? (Photos)

Always ask your surgeon as this will depend upon surgeon preference and the specifics of your surgery.
Most of my patients take off 7 to 10 days. Anything earlier is probably pushing the limit, but some of my patients have returned to light work after 5 days.
In addition, I tell my BBL patients to minimize sitting.  If they have to sit, it is critical that every 30 minutes or an hour that patients get up and stand for a few seconds to take the pressure off.   This reduces the chance for fat necrosis.  After 6 weeks the fat has revascularized, and you have a very good idea of your final results.  You will have to take it easy when returning to work with the heavy lifting.

Kenneth Hughes, MD, Board Certified Plastic Surgeon
Los Angeles, CA

Pressure recommendations will vary from physician to physician. The best advice is to discuss with your surgeon and adhere to his/her recommendations.
Offloading is crucial. Excess pressure can affect the viability of the nascent fat grafts. 
In my practice we provide compression garments this is combined with Reston foam and a custom tailor to ensure appropriate fit. With regards to pillows, the "Booty Buddy" is most popular but there are many available alternatives.
However, the best pressure is no pressure. I have found that pillows are often times taken as license to sit. I recommend patients strictly avoid direct pressure for at least 2 weeks followed by progressive incremental increases (with a goal of 1 hour uninterrupted by 1 month post op). You may have some flexibility as your graft target area is hips rather than buttocks. However, this is best discussed with your operating surgeon.
As always, discuss your concerns with your board certified plastic surgeon (ABPS).

Thank you for your question and posting appropriate pictures. You seem to be great candidate for fat grafting. I require my patients not to sit on their bum for 2 weeks after surgery. Having said that, it seems where you want grafting is not exactly where you would sit. In most cases I recommend taking 1 week off from work. You would need a consult for precise recommendations either in person or via Skype or FaceTime.